Cease and desist letters are formal documents sent by a trademark owner to an alleged infringer, demanding that they stop using a trademark that is believed to be infringing on the owner's rights. These letters serve as a warning, outlining the alleged infringement and the potential legal consequences if the infringing activity does not cease. They are often a first step in protecting trademark rights both domestically and internationally, and play a vital role in brand protection strategies, especially in the age of social media.